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For DRIVERS, MECHANICS & FOREMEN.

10th February 1920
Page 29
Page 29, 10th February 1920 — For DRIVERS, MECHANICS & FOREMEN.
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Making a Sleeve Valve for a Knight Engine.

The sender of the following communication has been awarded the extra payment of Se. this week.

[2,055] " H.M." (West Bromwich) writes :—" It. doesnot fall to the lot of many mechanics to have to make a new sleeve valve for a Knight engine. It has occurred to me, , and as it may, in the event of an nilfortunate combination of circumstances, happen to anyone, I thought a description of the method which

I adopted Might interest your readers.

The first thing to do is to prepare the old sleeve as a pattern for the new one. It will have to he lined up, so as to provide allOwances, for machining and shrinkage. A piece must be added to one end., that at which the plug for the valve eccentric is attached, .so as to provide an extension piece for convenience in chucking. The casting must be of good-quality grey cast-iron, having a fine grain.. Having got the casting, the 'following are the operations, which have to be performed on it, in the order named :

" (1) Bore and turn extension piece ; (2) rough bore

and turn the sleeve ; (3) rough grind the outer surface ; (4) cut off the extension piece ; (5)' score or groove for lubrication. ; (6)• mill the lug and ports; (7) machine finish the bore; (8) grind the bore ; (9) grind outside.

"The first operation, of boring and turning the outside to fit the chucking appliance, is shown in Fig. I of the sketch which I enclose. (We have had it re

drawn.—En.) The edge of the hole in the extension piece of the valve should be chamfered to snit the centre on the grinding machine.

"(2) The rough boring and turning may be done simultaneously if there is a turret lathe in the shop ; if not, and the work has to be. done in an engine lathe; the two operations may be carried out sepa-rately-.. The inside bore should have an allowance of 1.5 millimetre for finishing and grinding. The outside may have one millimetre left on for the same purpose. The bore of the sleeve at this end, too, should be bellmouthed, or chamfered, to fit the cotter-on the grinding machine. "(3) The Outside surface must now be ground to within .half a millimetre of the finished dimensions, and it must then be a good fit in the special attachment which is shown in Fig. 2. This operation should be performed with a 24K Alundum wheel. (5) and (6) may be carried out in any convenient manner, depending on the machirie'tools available ; when they are completed, the sleeve is ready to undergo operations " (7) and (8). For these the sleeve is pushed into the special fitting to which I have already referred .; it is prevented from turning by a, clamp which holds the lug on the sleeve. For the boring operation, an ordinary.bar is used, -with supporting bushes at each end. Two roughing cuts are taken, and one finishing. The latter should leave from one-tenth to one-fifth of a millimetre to be taken off during grinding.

"The final operation, that of grinding the outer surface, is accomplished with the sleeve mounted on an ordinary arbor."


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